Hello Everyone,

If you are reading this you must have listened from a lot of people about the importance of ‘The OSI model’ in networking. Let me present you with a quick read on the mentioned topic……………………(Here, we start)

It’s all about -

• PHYSICAL LAYER — — — — — — —(Layer 1)

• DATA LINK LAYER — — — — — — — (Layer 2)

• NETWORK LAYER — — — — — — — -(Layer 3)

• TRANSPORT LAYER — — — — — — — (Layer 4 )

• SESSION LAYER — — — — — — — — (Layer 5)

• PRESENTATION LAYER — — — — — (Layer 6)

• APPLICATION LAYER — — — — —(Layer 7)

• (A) PHYSICAL LAYER — — — — — — — - (Layer 1)-

  • Here, The data is transmitted over the network in the form of bits.

  • Examples- Ethernet Cables, Fibre Optic Cables, Hubs, Wireless Access Points, Bluetooth, etc.

• (B) DATA LINK LAYER — — — — — — — (Layer 2)-

  • Here, encapsulation of data into frames takes place. Then, the transmission of these frames takes place over the network.

  • Detection of error and it’s correction also takes place here.

  • Another function includes Identification of network devices using their MAC address.

  • This layer is also responsible for flow control.

  • Examples- Switches, Bridges, etc.

• (C) NETWORK LAYER — — — — — — — -(Layer 3)-

  • Whenever we talk about this layer, we talk about routing, addressing(IPv4, IPv6), Switching, etc.

  • Here, data flows in the form of packets.

  • Examples- Routers for traffic forwarding, IPv4 Protocol and IPv6 Protocol for IP addressing, Internet Control Message Protocol (ICMP) for troubleshooting, etc.

• (D) TRANSPORT LAYER — — — — — —- (Layer 4 )-

  • Here, the concept of TCP(Transmission Control Protocol) and UDP(User Datagram Protocol) comes into play.

  • If you are wondering what are the above-mentioned protocols. You can find out about them on the internet pretty easily.

  • The only thing I should mention here is TCP is more reliable (due to 3-way handshake method) than UDP.

  • Whenever data travels in this layer, it's in the form of SEGMENTS (if using TCP) or DATAGRAMS (if using UDP).

  • Examples- TCP, UDP, Firewalls, etc.

• (E) SESSION LAYER — — — — — — — — (Layer 5)

  • The main purpose includes setting up sessions, maintaining these sessions and closing a session

  • Here, the session is basically a connection or a conversation that is kept separate from other sessions.

  • Examples- NetBIOS (Used by computers to share files over a network)

• (F) PRESENTATION LAYER — — — — — -(Layer 6)

  • In this layer data formatting(for proper compatibility between devices) and data encryption takes place.

  • Example- Open any mail you had received. In that mail press on view details. there will be a field mentioned as security in there, which is designated as TLS(Transport Layer Security). If it’s not TLS then please be careful.

  • Other Examples- SSL, GIF, JPG, TIF, SVG, PNG, HTML, XML, PHP, JavaScript

• (G) APPLICATION LAYER — — — — — — (Layer 7)

  • This layer provides application services.

  • With the help of these services, user communicate with the computer.

  • Example- Domain Name Service (DNS), Remote Access (TELNET, SSH), Web Browsing (HTTP, HTTPS), E-mail (POP3, IMAP, SMTP) etc.

Well, you can put it like this (To Remember)-

Perfection_Do_Not_Tell_Someones_Positive_Attitude

or

You can make your own short key phrases

Make your own key phrase using these 7 layers and

Comment down below